Carburetor



April 1943. w. E. LEIIBING fi m CARBURETOR Filed Oct. 1, 1940 2Sheets$heet 1 April 6, 1943.

W. E. LE IBING CARBURETOR Filed Oct. 1, 1940 2 Sheets-Sheet 2 William, EW 1* m Patented Apr. 6, 1943 CARBURETOR William E. Lcibing,

Detroit, Mich, assignor to Lcibing-Fageol Company, partnership composedof F.

Detroit, Mich., a R. Fageol, Ravenna, Ohio; R. D. Fageol, Detroit,Mich.; Jessie M. Fageol, Ravenna, Ohio; W. E. Leibing, De-

troit, Mich; and

D. C. Famsworth, Veterans Hospital, San Fernando,

Calif.

Application October 1, 1940, Serial No. 359,282

(Cl. BBL-34) 8 Claims.

The present invention relates to improvements in carburetors forinternal combustion engines, and more particularly to that class ofcarburetors in which the throttle valve for controlling the flowsthrough the fuel conduit is positioned on the atmospheric side, orup-stream side, of the jets controlling the flow of fuel through thedevice, such a carburetor being sometimes known as the anterior throttletype. However, it is to be understood that a number of the featuresdisclosed herein are applicable a well to carburetors of any type.

Carburetion of the type described above has always been difficult andcomplicated. In an effort to solve the problems of such a carburetor,the prior art has resorted to complicated metering devices employingextremely accurately ma chined metering pins and like means, all ofwhich materially increase the costs of manufacture and the upkeep.Present day standard carburetors have also become very complicated inprinciple to a point where the average mechanic fails to understand saidprinciple and is therefore entirely unable to make any correction orrepair to the instrument. Factory-trained men who are equipped with jetsof different sizes and substitute parts of different characteristicsare, perhaps, the only personnel who can be trusted to make asatisfactory adjustment on a carburetor.

Present day accelerating pumps, used to cover the hesitation stage inacarburetor when the throttle is opened. are not entirely satisfactory inthat their points of discharge into the carburetor conduits the engineand be subject to a number of eddy currents. Furthermore, thearrangement of the pump is sometimes such that fuel is constantly beingsucked therothrough during operation of the engine, unless specificpreventive means in addition. to the normal pumping mechanism isprovided. and more complications.

In prior carburetors. reliance has been principally had upon thevcnturis employed therein to insure the proper mixture at all throttlepositions. By reason of the inherent characteristics of such vcnturis asregards their development of kinetic energy they cannot be relied uponexcept in full open throttle position. In rll other ositions, theirperformance is virtually indeterminable. In an effort to meet thisdefect in the venturis, metering devices have been adopted which areboth complicated and expenare often at points where the Efuel must passthe throttle valve before entering This necessitates additional expensesive, and at best have not been entirely satisfactory.

In overcoming the aforesaid disadvantages, it is a major object of thiinvention to provide a carburetor having novel and relatively simple andinexpensive metering means whereby all socalled metering pins, theirtubes, and like complicated and expensive devices, are eliminated.

A further object of this invention is the provision of a carburetorhaving novel means for controlling the fiow of fuel wherein the effectof the variable characteristics of the venturi are eliminated, except atstages of operation wherein the venturi can be depended upon to functionconsistently and correctly, as at wide open throttle.

A further object of this invention is to provide a novel carburetorwherein the air-fuel ratio for any given position of the carburetorthrottle can be made richer or leaner without influencing any otherposition of the throttle.

Still a further object of this invention is the provision of a. novelcarburetor having means to better atomize the fuel and obtain a morecorrect mixture of fuel and airfor securing better economy.

A further object of this invention is to provide a novel carburetor of adesign to eliminate the discharge of obnoxious gases and unburned fuelfrom the exhaust of an engine equipped with such a carburetor.

Still a further object of this invention is the provision of novelidling means for a carburetor whereby a more economical and efficientflow of fuel to the engine at idling speeds, and in a. condition betterto be consumed, is secured.

A further object of this invention is the provision of a novelcarburetor having a booster pump associated with the idling meanswhereby the function normally assumed by the conventional acceleratorpump is taken over bythe idling jet in more efficient manner, and anumber of parts in the carburetor, hitherto considered necessary,eliminated.

Referring to the drawings Figure 1 is a plan of a carburetor embodyingthe present invention taken on the 1ine-l-| of Fig. 2.

Fig. 2 is a section taken on the line 2-2 of Figure 1 illustrating indetail the metering mechanism and the fuel pump.

Fig. 3 is a section taken on the line 3-3 of Figure 1 showing across-section of the carburetor conduit and the relation of the idlingjet to the carburetor throttle.

Fig. 4 is a section taken at right angles to the section of Fig. 3, andon the line 4-4 of Figure 1. illustrating the manner of utilizing thecarburetor throttle shaft as a part of the fuel feeding means for themain jet of the carburetor in conjunction with the metering mechanism.

Fig. 4a is a section similar to the section appearing at the right sideof Fig. 4;, except that the fuel metering mechanism is shown in theposition corresponding to open position of the throttle.

Fig. 5 is a front elevation of the preferred form of plug used to formthe idling jet.

Fig. 6 is a side elevation of the plug of Fig. 5 with the plug rotated90 degrees.

Fig. 7 is an enlarged section of the plug as it appears in Fig. 3.

Fig. 8 is a section taken on the throttle shaft coincident with theconnection of the bore in the throttle shaft with the passage leading tothe main jet, and showing the position in which the main jet isdisconnected from its fuel supply, as occurs in closed position of thethrottle.

Fig. 9 is a view similar to Fig. 8 showing the throttle shaft rotated toa position where the main jet is connected to the fuel supply.

The present invention is described for the purpose of illustration inconnection with a carburetor of the so-called down-draft type, thearrows indicating the direction of the flow of fluid through thecarburetor. In all the figures. corresponding numbers are employed toindicate like parts.

Referring to Fig. 3, which illustrates the fuel conduit of thecarburetor, a housing If is provided with a flange l2 formed withapertures l3 and I4 therein for attachment to the intake section of anengine intake manifold (not shown) in well known manner. Directly aboveflange l2 and either made integral with housing i I, or arranged forinsertion therein, both arrangements being conventional practice, aventuri I5 is provided with the usual shaped orifice centrally locatedwithin housing If. Directly above venturi i5 is the central bore iii ofthe conduit in which is positioned a butterfly valve i'i. Valve i1 ismounted for oscillation in conduit l6 by means of a shaft It, the valvebeing secured thereto by suitable fastening means, such as screws f9.

Adjacent the upper righthand edge, or leading edge. of throttle l1 tion,as shown in Fig. 3, housing i i is formed with a horizontally extendingboss H with an aperture for receiving an idling jet plug 22, a detaileddescription of which will be later given. A cover or upper housing 23 ispositioned above housing I I, and is arranged to be secured thereto bysuitable flan es and fastening means not shown. Housing 23 is providedwith an air bleed passage 24 which registers with a passage 25 inhousing H to connect a passage 26 in housing 23 with the aperture formedin b ss N. A needle valve '21 is mounted on a boss 28 formed on housing23, as shown in Fig. 3. to control the passage 28. A spring 29 ispreferably provided in con unction with valve 21 to form a frictionallock and maintain the valve in its ad usted position.

Aperture 20 in boss 2| is connected by a conduit 3! to the bottom of afloat chamber. 32 (Fig. 2) formed on one side of housing H as shown inFig. 1. and dis osed substantially entirely to one side of shaft i8, asshown in Fig. 1. The upper portion of the float chamber is subject toatmospheric pressure by reason of a passage opening into section 23 ofthe carburetor conduit (Fig. 4).

when in its closed posiretor is used is a minimum.

check valve As shown in Fig. 1. throttle shaft It extends into the floatchamber and terminates at a point approximately midway thereacross. Ametering device, or arm, 33 (Fig. 2) is secured to the float chamber endof shaft Is in a manner to rotate therewith, arm 33 being formed in whatmight be called a bent-arm fashion, the elbow 35 of which is alwayspointed outwardly and downwardly when viewed as in Fig. 2. Bent-arm 33comprises an upper arm section 34 ex ending from shaft id to elbowsection 35, this upper arm section being substantially horizo tal asviewed, and a forearm section 36 extending substantially vertically fromelbow section 35. A passag 31 is formed within upper arm section 34,passage 3! connecting with a passage 38 in forearm section 36. Forearm36 is preferably formed in a shape approximating the arc of a circlewhich has as its center shaft l8 to insure the entrance and exit offorearm 36 into the fuel at the same point at all times, namely. at thecenter of the chamber where the change in level of the fuel by reason ofthe vibration and various inclinations of the vehicle on which thecarbu- Passage 38 in forearm section 36 is preferably formed by a seriesof straight bores, as shown, to facilitate manufacture, the bores beingplugged at their outer ends by plugs 39 and 4 l.

Preferably a series of spaced metering apertures 42 which constitutemetering means, shown for illustration to be 13 in number, are providedin forearm section 36 communicating with the space in the float chamberand with passage 38. While a series of successive apertures have beenillustrated, it is to be understood that a series of slots, one longslot, or openings of other shapes, may be provided as found desirable incertain specific installations.

As shown in Fig. 4, throttle valve shaft I8 is bored at its right end,or the float chamber end, to form a main fuel conducting passage 43extending for some distance within the shaft to a point above a bore orfuel passage 44 formed in the housing II. To connect bores 43 and 44, across fuel passage 45 is provided in shaft l8, as shown in Figs. 8 and9, passage 45 being positioned to be in alignment with vertical passage44 in housing If when throttle valve i1 is in wide open position, asshown in Fig. 9, and to be out of alignment and close the connectionbetween bores 43 and 44 when the throttle valve is in closed position,as shown in Fig. 8. To vary the point at which the connection is madebetween 43 and 44, a second cross drilling 45 is preferably made inshaft l8, the size and position of which may be varied to provide for aconnection between bores 43 and 44 at any desired point in the openingofthrottle valve l1.

Vertical bore 44 terminates in a cross passage 41 which is preferablyenlarged at its left end where it opens into conduit iii to receive oneend of a curved tube 48, the lower or outlet end 49 of which iscentrally located at the point of highest velocity in venturi l5, thetube 48 and its end 49 becoming the main jet of thecarburetor. Tube 48is preferably secured in passage 41 as by swaging, the tools for whichmay be conveniently introduced through a 'hole normally sealed by a plugfat, as shown in Fig. 4.

Referring to Figs. 1 and 2, a pump cylinder 52 is provided in floatchamber 32 of housing H, a 53 of conventional character being providedat the lower end of pump cylinder 52 whereby fuel is free to pass out ofthe cylinder into tube 3| leading to the idling jet. but cannot flowback into the cylinder. Tube Ii leading to the idling jet is connectedto the housing below check valve 53 in fluid tight relationship, a plug84 being preferably provided to facilitate assembly and the cleaning ofthe parts.

A pump piston I8 is provided to reciprocate vertically in cylinder 52,the piston being provided with a piston rod 58 working in a guide 31mounted in the upper part of the float chamber. A disc 68 is secured topiston rod 58. A spring 58 of the helical compression type, andpreferably tapered, is provided between disc 58 and the upper part ofthe float chamber housing, this spring always tending to urge pumppiston 55 toward the bottom of pump cylinder 52 and inject fuel throughtube 3| into theidling jet and from there into conduit l8.

Piston 55 is formed with a plurality of bores II and a check valve 62 ofthe disc type, whereby fuel may freely pass from the float chamberthrough bores 8i and out of passage 3i, but cannot pass in the oppositedirection. Obviously when piston 55 is moved downwardly by spring 59,check valve 82 closes, and the fuel in cylinder i 52 is forced outthrough conduit 3|. When piston 65 is stationary, check valve 62 will beopen and a free flow offuel through bores 6| will be assured.

Forearm section 33 of metering device or arm 33 is provided with a lugor abutment 33 which is positioned to engage disc 58 and raise piston 65against the force of spring 69 when the throttle goes to closedposition, abutment 83 swinging downwardly when the throttle is opened,mitting discs 53 to lower and fuel to be forced into tube 3| by reasonof the pressure of spring 59. As lug 63 does not engage disc 58 duringthe lower portion of the swing of arm 33, the pump is obviously operatedto pump fuel only during the initial stage of movement of arm 33corresponding to the initial opening movement of' the throttle. When thethrottle shaft is rotated to close the throttle, arm 33 swingsclockwise, whereupon lug 63 raises the piston, thus reloading the pump.

Adjacent to and preferably equidistant from metering device 33 is a pairof floats 84 and 63 secured to a U-shaped lever 68. Lever 88 is pivotedon a shaft 61 in the float chamber which, in turn, is supported by abracket 68 attached to the carburetor housing. The upper surface oflever 66 contacts the lower end of a vertically reciprocal needle valve69 which operates in a removable plug Iii having a valve seat II, thisassembly acting to maintain a constant level of fuel within floatchamber 32, and either shut off or admit fuel, as the necessity mayarise in the operation of the engine. A fuel line, not shown, ispreferably attached at threadedhole 12, the passage of fuel therefrombeing governed by needle valve 68.

Referring back to plug 22 which is used to form the idling jet, andreferring specifically to Figs. 5, 6, and 'l, which are enlarged viewsof the plug as viewed in Fig. 2, the plug is formed roughly as a solidcylinder. the left end thereof, as viewed in Figs. 5. 6, and 7, beingprovided with a transverse slot 13 which extends inwardly to a point M(Fig. 6) and communicates with a metered orifice leading to a large boreor passage 76 within the interior of the plug. The plug is recessed toprovide an annular recess I1 and an annular recess 18 which form annularchambers I3 and 3|, respectively, (Fig. 3) with the inner walls of andperengages disc 58 of the pump and aperture 20 in boss 2|, the plugbeing of a size such that chambers 18 and if are sealed from one anotherin fluid tight relation. As shown in Fig. 7. slot 13 extends back intothe annular recess 11. Bore 18 is connected to annular recess 13 bytransverse bores 32. At its right end, bore 13 is preferably threaded toreceive a screw 83 which is normally tightened to close the outer end ofthe bore, and can. be removed to readily clean the plug and remove anyobstructions in the idling jet. As compared with prior carburetorswherein the idling jets have been virtually hidden away in the interiorof the carburetor, and any clogging thereof has necessitated a completedisassembly of the device, the idling jet of the present invention isextremely easy to clean. The only thing that must be done is removescrew 83 and access is readily had to the interior of the jet.

By reason of slot 13, annular chamber 19 is in metered relation with theatmosphere at its left side through the area of slot 13 up-stream of theedge of throttle valve l7, and is in metered relation with theatmosphere through the passages 24, 25, and 26.

When plug 22 is assembled with a carburetor, annular chamber 8|communicates with the upper end of conduit 3i Fig. 3), chamber 3| thusbecoming a fuel chamber from which raw fuel is fed in metered relationthrough metering Jet 15 into slot 13. By reason of the meteredatmospheric air present in chamber 79 and slot 13, air is immediatelymixed with the fuel discharged from Jet 16, and the resultant air andfuel mixture discharged adjacent the leading edge of the carburetorthrottle valve l1.

By reason of this arrangement, the fuel and air to be discharged fromthe idling jet are not mixed until just prior to their discharge fromthe jet. This is of advantage compared with the prior constructionswherein attempts have been made to mix the fuel and air sometime priorto their actual discharge from the idling jet, and the fuel and airmixture has been required to travel through a number of tortuouspassages. Becausev of such passages, the fuel and air mixture has tendedto separate. as a result of which a series of globules of fuel separatedby air pockets have been discharged from the idling jet rather than ahomogeneous mixture of fuel and air.

When assembled, carburetor throttle valve I1, or rather, the leadingedge thereof. lies adjacent the left end of plug 22, and in itsfurthermost closed position will appear approximately as shown in Fig.7. at which point it will be noted that a small amount of transverseslot 13 is located down-stream from throttle ll, while a far greaterarea of slot 13 is located on the upstream side of the throttle. andtherefore open to atmospheric pressure. When the throttle goes from afull closed to a full open position, it will traverse slot 13 andthereby simultaneously increase the amount of the slot down-stream orbelow the throttle and decrease the amount of slot above or up-stream ofthe throttle.

It will be noted in the carburetor as described an idling jet isprovided in combination with an anterior throttle, the main supply jetunder normal running conditions being positioned between the throttleand the intake of the engine adjacent the venturi.

Method Of operation If it be assumed that the carburetor as thus fardescribed is assembled with an internal comi relieve the vacuum,

with the engine idling and the throttle valve H in its furthermostclosed position, as shown in Fig. 3, a vacuum of approximately 18 to 20inches of mercury will exist down-stream of the throttle in conduit IS.The area of transverse slot 13".down-stream of the throttle valve willtherefore be subject to such vacuum which will be effective through slot13 upon annular chamber 19 and through jet l and transverse bores 82uporilannular chamber 8|. However, as the upper exposed portion of slot13 is of a greater area than'the lower portion, and it is up-stream ofthe throttle valve, and therefore subject to substantially atmosphericpressure, considerable air enters. slot 13 and relieves this vacuum tosome extent. Additional air is also free to enter by way of passages 24,25, and 26, and further this amount of air being regulated by theadjustment of screw 21 to a. point where just sufficient fuel is drawnfrom jet to meet the requirements of the engine at this phase ofoperation. Any shutting off or diminishing of the air admitted by way ofaperture 26 will increase the amount of fuel drawn from jet l5, and anyincrease in the amount of air admitted by hole 26 will correspondinglydecrease the amount of fuel drawn through jet 15.

Any movement of valve l1 towards an open position will change therelation of the portions of slot 13 exposed up-stream and down-stream ofthe valve, and thereby increase the proportion or amount of the slotexposed to the high vacuum down-stream of the valve and decrease theamount of the slot exposed to atmospheric air. Thus the vacuum acting onthe jet 15 will be increased. Correspondingly, the amount of fuel fedtherethrough will be increased and the requirements of the engine met.

This arrangement possesses advantages not found in the prior art. In theprior art, it has been customary to 'use but one groove or chamberconnecting with the idling jet into which single groove is fed both theraw fuel and the air. Furthermore, the metering orifice or othermetering means for the raw fuel is often removed a considerable distancefrom the point of discharge of the idling jet into the carburetor con=duit. It has been found by actual experiment that such a design tends tomake any single annular chamber perform as a collector in which a dropor two of fuel first collects and is then discharged as raw fuel ratherthan as an emulsion. With the present arrangement, the raw fuel neverenters the annular chamber I9, but is delivered direct to slot 13wherein the space is so confined. and the distance it is to travel soshort before being discharged into the main bore of the carburetor) thatthere is no possible chance for separation of the fuel and air, oraccumulation of raw fuel. The mixture thus discharged is homogeneous,and is fed in an even, continuous fiow which greatly improves the engineperformance at idling.

Referring back to Fig. 2, it will be noted that during the abovedescribed idling operation, all

the apertures 42 in the forearm section 36 of the metering device arewell above the float level FL and that any leakage through the jet 49 byreason of the vacuum effective thereon can only draw air at atmosphericpressure from the upper portion of the float chamber 32. Furthermore,when the carburetor throttle valve is in a position whereby the engineis idling, shaft I8 is in the position shown in Fig. 8, whereby passage44 and consequently jet 49 are completely shut off from the fuel supply.

To further insure against the introduction of fuel under idlingconditions through jet 48, and

possibly around the portion of the housing supporting the right end ofshaft l8, as viewed in Fig. 4, a series of annular recesses 84 are outin shaft l8 at positions to register with passages 85 leading to theatmosphere. This bleeding of atmosphere in and around the bearingsupporting shaft l8 prevents the sucking in of any undesired fuel intothe carburetor conduit around the bearing.

To further prevent any undesirable siphoning action by reason of theconnection of jet 49 to the float chamber, the end of bore 43 in shafti8 is preferably plugged by a plug 88 which has a small metered orifice81 therein open to the area of the float chamber above the fuel level,which is open, in turn, to the atmosphere. Orifice 8'! permits the entryof a restricted amount of air, and prevents any siphoning action.

The above described idling arrangement has been found to be furtheradvantageous inasmuch as when the fuel at idling is discharged from thedown-stream portion of slot 13, it is at such a point that the fuel mustpass the venturi it, which is positioned between the idling jet and thecarburetor outlet. From actual observation through glass manifolds, ithas been found that with the present invention, venturi l5 operates toeven out the fuel flow, which includes both air and fuel, and todischarge it in a uniform, invisible, homogeneous mixture. In presentstandard carburetors of the interior throttle type, like observationsshow that the idling mixture is discharged unevenly, with the raw fuelfollowing one path, and the air following another path. The manner inwhich the fuel is mixed and thereafter handled in the present inventionis of utmost importance in providing gas-free operation during allrunning conditions, and also during decelerating phases, as when the caris driving the engine. as occurs in descending a hill when the engine atclosed throttle is being used as a brake.

Taking up the second phase of operation of the carburetor, as the enginegoes from idling position to a phase of operation where the throttlevalve is moved to a further open position, the operation above describedapplies equally well to the first stages of movement of the carburetorthrottle valve, and hence will not be repeated.

As the throttle is opened from closed position towards an open position,the area of slot 13 down-stream of the throttle valve will be increased,causing a higher vacuum to be effective upon jet 75, while at the sametime the area of slot 13 existing up-stream of the throttle isdecreased, thus further increasing the vacuum effective upon jet 15.Such increase in vacuum results in increased fuel flow, and assumingthat the size of jet 15 and the width of slot i3 have been properlyselected and coordinated, the throttle valve may continue to open untilthe entire area of slot l3 has beentransferred to the down-stream sideof the throttle valve. During all stages of this movement, the mixturewill remain correct as regards the air-fuel ratio, and the operation ofthe engine will be correct. .As slot 13 becomes fully exposed to the hih vacuum down-stream of the throttle valve, the maximum amount of fuelis being drawn from Jet 15. If no further means were employed, thisposition of the carburetor throttle would constitute a limit beyondwhich the valve could not open without radically affecting the air-fuelratio to a degree where the engine would not function. However,coincident with the throttle valve arriving at this position, the firsthole of series 42 in the forearm section 36 dips into the fuel of thefloat chamber, and a small amount of fuel is added through jet 49 to thehigh velocity air passing through the carburetor, the connection betweenpassage 44, slot 46 and passage 45 having been made by the valve movingtoward open position.

Further movement of the throttle valve toward open position immersesadditional holes 42 below the fuel level, and increases the capacity ofthe forearm section 36 for fuel. 'I'hus, more and more fuel is fed tothe mixture emerging from jet 49, until the throttle valve is wide open,and all holes of the 42 series are being fed fuel. It is to beunderstood that in partially open position of the throttle valve, whereall of the holes 42 are not immersed, a certain quantity of airdetermined by the number of holes 42 above the fuel level in the fioatchamber may be drawn into the passages 38 and 31 and mixed with the fuelbeing sucked therein. This quantity of air will be determined by thesize of holes 42 and the number thereof that are immersed.

As jet 49 is positioned considerably below the float level in the floatchamber, and is in fluidtight relationship with shaft l8, it is apparentthat if the engine were left at wide open throttle and the ignition shutoil, or if a heavy load sufilcient to bring the engine down topractically idling speed were imposed on the engine, then in both casesjet 49 would siphon fuel from the fioat chamber. Such siphoning isprevented by the metered orifice 81 in the right end of shaft l8, whichpermits the leak of atmosphere into the fuel line at a point well abovethe fuel level in the float chamber, and effectively prevents suchsiphoning action.

It is further apparent from the above that at any position of thethrottle valve after the first hole in the 42 series has been submergedin the fuel, a rich, a lean, or the correct amount of fuel can besecured without in the least upsetting some position further along inthe scale.

Referring to the final phase of operation, or the means functioning tosupply the various types of mixtures required by change in loadconditions without any change of throttle position, a heavy loadrequires a somewhat richer mixture than a light or no load. If it beassumed that there is a light load with a throttle position equivalentto 3 of the 42 series holes beneath the fuel level, the other holes ofseries 42 would be delivering a considerable amount of air, and Jet 49would be discharging an emulsion of air and fuel at high velocity.

If the throttle is left at the position where 3 of the 42 series holesare submerged and a load sufficient to almost stall the engine isapplied, there will be light flows passing through passage 44 and jet49, and the 10 holes of the 42 series above the fuel level will beentirely ineffective as regards a supply of air to jet 49 because of thefuel flowing into the interior of the bent arm section by way of the 3holes of the 42 series below the fuel level. Thus the mixture dischargedfrom Jet 49 has been converted from ten parts of air to three parts offuel (figuratively) to no air and three parts of fuel, so that Jet 49 isdischarging fuel diluted only by the air admitted by the siphon break81.

This follows because of the very low vacuum effective through passage 31upon bore 38, this vacuum being only suflicient to utilize the capacityof the 3 holes of the 42 series immersed below the fuel level. Undersuch conditions, elbow section 35 which is immersed below the fuel leveloperates as a liquid seal to prevent the passage of any air from theholes of series 42 above the fuel level into passage 31, and from thereinto Jet 49.

To illustrate this action still further, let us assume the engine isshut off with the throttle valve I! still in the described position. Itis readily apparent that the 3 holes of the 42 series below the fuellevel will permit the fuel to enter the arm 33 and seal of! from theoutlet hole 31 the remaining 10 holes of the 42 series so that anyresumption of fiows in hole 31 towards the shaft 19 must be first of asolid fuel.

The aboveapp'lies to all positions of the throttle valve up to wide openposition, at which point a slightly different operation occurs. Whetherthe engine be under light load or under heavy load, all holes of the 42series are below the fuel level in the float chamber, and therefore nochange in the output of the metering device as regards the air-fuelratio can occur. Therefore, it would appear that no correction ofmixture as regards load occurs. However, it must be remembered that thisoccurs only at wide open throttle position, so that for the first timein the operating sequence venturi i5 is really effective as to thekinetic energy developed by Jet 49- located at the most advantageouspoint in venturi IS. The venturi, in controlling for this one provenitself well able to control the fuel fiows within required limits.

In other words, as compared to the operation of a venturi in an interiorthrottle carburetor wherein the venturi functions in throttled as wellas in unthrottled position, and therefore has a range of operation sowide that it includes the well known variable of kinetic energy, tocorrect which all of the modern carburetor patent history is dedicated,in the present invention the during throttled positions, and hence itsvariable characteristics do not enter into the picture. Instead, in thepresent invention, during throttled positions, vacuum As regards theacceleration phase of the carburetor, practically all presentcarburetors are designed to' run on mixtures which are so lean furtheropen position results in hesitation" of the engine until the properflows charge on the atmospheric side of the throttle valve. where, dueto the interference of parts in the carburetor conduit, eddy currentsand other position only, has

factors, the results are not entirely satisfactory. Furthermore, sucharrangements are inclined to draw fuel in running positions, and furthermeans is required to eliminate this drawing of fuel which, of course,requires added structure with its attendant complications anddisadvantages.

In the present invention, the idling Jet is used as the outlet for theaccelerating device, thus accomplishing a considerable saving in partsand machining. Furthermore,.no means is required to eliminate flows whennot required. In the present device, the pump might better be describedas a booster pump on the idling system rather than as a separateaccelerating pump. As a result of actual tests, it has been found thatthe use of the idling Jet as a pump discharge jet is far superior to anyother arrangement.

It is to be understood that variousmeans of choking, well known to theart, can be employed in combination with the present carburetor for thepurpose of starting the engine when cold. .As such chokes do not formany part of the present invention, description thereof has been omitted.It is also to be understood that the carburetor throttle valve i! mayalso be utilized as a governing valve in accordance with well knownpractice. In the present illustration, for the purpose of brevity,idling and high speed limiting stops on throttle valve shaft i8 havebeen omitted as well as the conventional throttle rod mechanism formanually rotating the throttle valve shaft, together with its attendantspring means for normally maintaining the throttle valve in closedposition.

A still further advantage of the present invention resides in theability of the design to use a larger venturi than standard practice, ormodern carburation, will permit. Whereas in the standard type ofcarburetor, an extremely large venturi cannot be used due to the venturicontrolling and creating the partial throttle flow of fuel, in thepresent carburetor, the venturi controls only wide open performance. Asan example, a racing venturi could be used with no loss of performanceat /4 or A; throttle, while standard practice for racing carburetorswould render the engine extremely poor in operation at speeds of about20 to 30 miles per hour.

The present invention is also advantageous in that it has been found byactual trial that it is possible to design the carburetor to correctlycarburete any engine without changing the carburetor. For instance, ithas been found that when the carburetor was worked out for one type ofengine, it is possible to transfer it to an engine of an entirelydifferent type and still secure perfect performance.

It is to be understood that the invention may be embodied in specificforms other than that illustrated without departing from the principleor essential characteristics thereof. The embodiments shown aretherefore to be considered as illustrative and not restrictive, thescope of the invention being defined by the appended claims rather thanthe foregoing description and drawings. All modifications and changeswhich come within the meaning and range of equivalency of the claims aretherefore intended to be included therein.

I claim:

1. A carburetor for an internal combustion engine comprising a conduit,a throttle valve in said conduit, a shaft for supporting said valve, afuel jet in said conduit, a float chamber, said shaft being formed witha fuel passage connected with said fuel Jet, and means to connect saidfuel passage to said float chamber comprising a hollow -anm connected tosaid shaft to rotate therewith,

and extending outwardly therefrom, a portion of said arm being bentupwardly and being formed with a series of metering openings arranged tobe successively immersed in the fuel in said float chamber as saidthrottle valve is opened.

2. A carburetor for an internal combustion engine comprising a conduit,a throttle valve in said conduit, a fuel jet in said conduit, a floatchamber, a shaft to support said throttle valve, said shaft having apassage therein for a portion of its length, means to connect one end ofsaid passage to said fuel Jet, and means to conduct and meter fuel intosaid passage from. said float chamber comprising a conduit secured tosaid shaft to rotate therewith and extending outwardly therefrom, and asecond conduit at the end of said first conduit, said conduits beingrelatively positioned to form a substantially horizontal extending upperarm with a substantially vertical forearm when said throttle is inclosed or substantially closed position, the elbow section of said anmbeing positioned to enter the fuel in the fuel chamber first uponrotation of said shaft in a direction to open said throttle valve, theremainder of said arm being progressively immersed in the fuel as saidthrottle goes to open position, said forearm section being provided withfuel metering means distributed along its length 'to receive fuel fromsaid fuel chamber in a manner whereby its capacity for fuel is increasedas said throttle valve goes to further open position and said forearmsection is progressively immersed in the fuel.

3. The carburetor claimed in claim 2 wherein said fuel metering means onsaid forearm section is positioned substantially along an arc of acircle with the center of the circle substantially coincident with saidthrottle valve shaft for causing said metering means to be progressivelyimmersed at substantially the same point in said float chamber as saidthrottle valve shaft rotates to move the throttle valve to openposition.

4. The carburetor claimed in claim 2 wherein a fuel pump is providedwith means for normally urging said pump into pumping action, and meansis provided on said forearm section to release said means for operatingsaid pump during the initial stages of movement of said forearm sectionwith the opening movement of said throttle.

5. The carburetor claimed in claim 2 wherein said fuel metering means onsaid forearm section comprises a series of spaced aperturescommunieating with a central bore whereby the number of aperturesavailable for fuel flow is increased as said section is progressivelyimmersed in the fuel in said float chamber. 7

6. A carburetor for an internal combustion engine comprising a conduit,a throttle valve in said conduit, 9. fuel jet in said conduit, a floatchamber, a shaft to support said throttle valve and secured thereto torotate therewith, said shaft having a passage therein, means to connectone end of said passage to said fuel jet, and means to conduct and meterfuel and air into said passage from said float chamber comprising aconduit secured to said shaft and extending therefrom to move with thelatter and said throttle, a second conduit secured to the end of saidfirst conduit, said conduits being relatively positioned to form asubstantially horizontal extending upper arm with a substantiallyvertical forearm when said portion of air to fuel is decreased as saidthrottle valve goes to further open positions forearm is progressivelyimmersed in liquid fuel. 7. A carburetor for an internal combustionengine comprising a conduit, a throttle valve in said conduit, a shaftfor supporting said valve, a fuel jet in said conduit, a. float chamber,said shaft being formed with a fuel passage connected with said fueljet, and means to connect said fuel passage to said float chambercomprising a hollow upwardly bent arm, the outer portion of said armsaid arm being formed with metering means arranged to be progressivelyimmersed in the fuelin said float chamber as said throttle valve isopened.

8. The combination claimed in claim 1 wherein means is provided toconnect said fuel passage with said fuel jet at all positions other thanclosed position of said valve, and to disconnect said fuel passage fromsaid fuel jet when said throttle is in closed position.

WILLIAM E. LEIBING.

